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<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        {
            var arr = [];
            for(var i = 0;i<2;i++){
                arr[i] = function(){
                    console.log(i);
                }
            }
            arr[0](); //2
            arr[1](); //2 全局变量
        }
        {
            let arr = [];
            for(let i=0;i<10;i++){
                arr[i] = function(){
                    console.log(i);
                }
            }
            arr[0](); //0 
            arr[1](); //1
        }
        {
            let i = 0; //相当于 let i =0;
            arr[i] = function(){
                console.log(i);
            }
        }
        {
            let i = 1;
            arr[i] = function(){
                console.log(i);
            }
        }
    </script>
</body>
</html>